Production method of synthetic and yarn traverse device

ABSTRACT

In the process of drawing/heat treating synthetic fiber thread melted and spun via a plurality of godet rollers and subsequently winding the same, accumulation of extraneous matter on the surface of the godet rollers may be prevented by performing multistage drawing/heat treatment while reciprocating the thread in the direction of the axis of rotation of the godet roller using the godet rollers at least two of which have surfaces having the roughness of 0.5≦Ra≦5 and one of which has a surface at a temperature of at least (melting point of synthetic fiber−70° C.), whereby occurrence of thread breakage or generation of fuzz may be prevented and synthetic fiber whereof the rate of operation can be increased and efficiency of manufacture is improved may be obtained.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] In the manufacture of synthetic fiber, especially, of industrialfiber formed by drawing/heat treatment of undrawn thread by the use of aplurality of godet roller groups, the present invention relates to amethod of manufacturing high-strength synthetic fiber for maintainingdrawing/heat treatment of synthetic fiber stable for a long term byresolving problems such as thread breakage or generation of fuzz toavoid accumulation of extraneous matters on the surface ofhigh-temperature godet rollers, for increasing the rate of operation byreducing the number of times the machine have to be stopped for removingextraneous matters from the godet rollers, and for improving productiveefficiency by reducing abrasion of the surface of the godet roller, anda thread traversing device to be used directly in the same method.

[0003] 2. Description of the Related Art

[0004] In the manufacture of synthetic fiber as typified by polyamide orpolyester, among others, of industrial synthetic fiber, it is requiredto achieve high strength by heat drawing undrawn thread under largemagnification and high tensile stress generally by the use of aplurality of godet roller groups. Therefore, at least one of a pluralityof godet roller groups have to be set to high temperature in order toheat setting the thread drawn into a high magnification. Thisdrawing/heat treatment process of undrawn thread been suffering fromsuch phenomenon that attachment and accumulation of extraneous mattersdropped from the traveling thread on the surface of the godet rollerswith time causes abnormal states of drawing, which has a serious impacton the quality/appearance and productive efficiency of fiber obtained.

[0005] The abnormal states of drawing here include winding of travelingthread on the godet roller, generation of fuzz due to breakage of afilament of the thread, and breakage of the thread itself due toincrease in surface frictional force caused by the external mattersattached and accumulated on the surface of the godet roller.

[0006] There is recognized an unfavorable phenomena that the extraneousmatters attached and accumulated on the godet roller set at a hightemperature near the melting point of polymer block heat transmissionbetween the godet roller and the thread, which results in insufficientheat treatment of the thread, and thus variations in quality/appearanceof the obtained drawn thread with time. Since stain on the surface ofthe godet roller that is set to a high temperature may occur inrelatively a short time, and may cause the abnormal states of drawing asdescribed above, the process of cutting the thread compulsory regularlyor every time the abnormal states are detected, and stopping theoperation of the drawing machine to remove the extraneous matters on thegodet roller is made frequently. Therefore, the problem of lowering ofthe productive efficiency and of appearance of the product has been inthe news.

[0007] The conceivable accumulated deposits on the godet roller includeanchored matter generated mainly from spinning oil applied on the threadbeing transformed by heat on the drawing/heat treatment roller,oligomers separated out of the thread and those heat-transformedmatters, and silica contained in water.

[0008] The following related arts are disclosed as methods of avoidingand removing abnormal drawing due to accumulated deposits as describedabove.

[0009] For example, in Japanese Patent Laid-Open No.78364/1997 andJapanese Patent Laid-Open No.187469/1996, systems for cleaning theextraneous matters by bringing the scraper blade or the rotating brushinto contact on the surface of the godet roller are proposedrespectively. However, in the manufacture of industrial fiber, ahigh-temperature heated roller is used as a godet roller in many cases,and thus the aforementioned scraper blade or the rotating brush cannotremove accumulated deposits easily. In addition, since the thick threadis drawn by a high tensile stress, there is also a problem in that thedevices such as the scraper blade or the rotating brush mounted in thevicinity of the godet roller are frequently broken due to the threadwound on the roller after breakage of the thread.

[0010] In Japanese Patent Laid-Open No.170215/1996, a method andapparatus for reciprocating (traversing) a traveling thread on the godetroller by means of a thread guide in the field of manufacturing fiberfor clothes are proposed.

[0011] However, since the denier of threads being larger than fiber forclothes, threads are normally drawn to a large magnification in themanufacture of industrial fiber, occurrence of a single filamentbreakage or thread breakage is distinctive in comparison with themanufacture of fiber for clothes. In addition, since the surfacetemperature of the godet roller is set to the higher value than thatused in the manufacture of fiber for clothes, accumulation of extraneousmatters on the godet roller caused by heat-transformed spinning oil isdistinctive, and thus the impact on the appearance of the obtained yarnis clearly visible. Therefore, generation of transformed spinning oilcannot be sufficiently prevented simply by reciprocating the thread onthe godet roller by the use of the thread guide, and thus transformedspinning oil is accumulated on both ends of the reciprocating motion ofthe thread guide, which may result in increase in thread breakage orgeneration of fuzz with time. In order to a void such phenomena, themachine has to be stopped many times in order to remove the extraneousmatters on the godet roller, which impairs increase of the rate ofoperation.

[0012] In addition, in the manufacture of industrial fiber, drawingoperation aiding units such as an air guide for preventing a singlefilament breakage on the roller, a heat treatment cylinder for fixationof a drawing point, and a heat plate and a heat treatment cylinder foraiding drawing operation are provided among a plurality of drawingrollers in many cases, and thus misalignment between these drawingoperation aiding units and the traveling thread when the travelingthread is reciprocated, which may result in breakage of the travelingthread due to abrasion with these drawing operation aiding units.

SUMMARY OF THE INVENTION

[0013] Accordingly, in the manufacture of synthetic fiber, especially,of industrial fiber formed by drawing/heat treatment of undrawn threadby the use of a plurality of godet rollers, it is an object of thepresent invention to provide a method of manufacturing synthetic fiberfor maintaining drawing/heat treatment of high-strength synthetic fiberstable for a long term by resolving problems such as thread breakage orgeneration of fuzz, which are distinctive in industrial fiber, toperform high-temperature large-magnification drawing while avoidingaccumulation of extraneous matters on the surface of a high-temperaturegodet roller, for increasing the rate of operation by reducing thenumber of times the machine has to be stopped for removing extraneousmatters from the godet roller, and for improving productive efficiency,and a thread traversing device to be used directly in the same method.

[0014] In order to achieve the aforementioned object, the inventionprovides a method of manufacturing synthetic fiber comprising the stepsof performing multistage drawing/heat treatment on the thread ofsynthetic fiber formed by melt spinning using a plurality of godetrollers, and subsequently winding the obtained thread, wherein at leasttwo sets of godet rollers of the plurality of godet rollers have surfaceroughness Ra in the range of 0.5- 5 μm, wherein at least one set ofgodet rollers out of these godet rollers have surface temperatures notless than (the melting point of the synthetic fiber−70° C.), and whereinthe thread is reciprocated in the direction of the axis of rotation ofthe godet roller.

[0015] In a method of manufacturing synthetic fiber according to theinvention, the following points (a) to (e) are preferred modes of theinvention respectively, and by applying these conditions, morepreferable effects can be expected.

[0016] (a) The tensile stress of the thread is not less than 1.4 cN/dtexin the last drawing step of the multistage drawing;

[0017] (b) Total denier of the thread of the synthetic fiber is not lessthan 200 dtex;

[0018] (c) The thread is a multi-thread including at least two lines ofthread;

[0019] (d) The cycle of the reciprocating motion of the thread is atleast 5 seconds.

[0020] (e) The width of reciprocating motion of Y(mm) satisfies thefollowing expression (1).

XF≦Y≦2(XP−XF)  (1)

[0021] where;

[0022] XF is the width of the thread (mm), and XP is the thread pitch(mm) between the adjacent threads.

[0023] In the manufacture of industrial fiber involving drawingoperation aiding units, in order to solve the problem in that fuzz tendsto be generated by abrasion of the traveling thread with the drawingoperation aiding unit when the thread is moved, the invention provides amethod of manufacturing synthetic fiber comprising the steps ofperforming drawing/heat treatment on the thread of synthetic fiberformed by melt spinning with a plurality of godet rollers, andsubsequently winding the obtained thread, wherein the thread isreciprocated in the direction of the axis of rotation of the godetroller while synchronizing a thread converging guide for allowing thethread to pass through before and/or after the thread is wound aroundthe godet roller located immediately after the spinning duct and one orplurality of drawing operation aiding units disposed between theplurality of godet rollers. In this method of manufacturing syntheticfiber, the following points (f) to (j) are preferred modes of theinvention respectively, and by applying these conditions, morepreferable effects can be expected.

[0024] (f) The drawing process is a multistage drawing process includingat least two stages.

[0025] (g) The thread is multi-thread including at least two lines ofthread.

[0026] (h) The drawing operation aiding unit is a thread entanglingdevice.

[0027] (i) The width of reciprocating motion Y (mm) satisfies thefollowing expression (1):

XF≦Y≦2(XP−XF)  (1)

[0028] where;

[0029] XF is the width of the thread (mm), XP is a thread pitch (mm)between the adjacent threads.

[0030] (j) The cycle of the reciprocating motion is at least 5 seconds.

[0031] The thread traversing device according to the invention is adevice to be used for a method of manufacturing synthetic fiber in whichthe thread of synthetic fiber formed by melt spinning is drawn/heattreated and then wound by a plurality of godet rollers, comprising athread converging guide for allowing the thread to pass through beforeand/or after the thread is wound around the godet roller locatedimmediately after the spinning duct, an drawing operation aiding unitdisposed between a plurality of godet rollers, and means forsynchronizing the thread converging guide and the drawing operationaiding unit.

[0032] In the thread traversing device according to the invention, thefollowing points (k) to (p) are preferred modes respectively, and byapplying these conditions, more preferable effects can be expected.

[0033] (k) means for synchronizing the thread converging guide and thedrawing operation aiding unit comprises a driving motor, a shaft mountedon the driving motor in the direction of the axis of rotation of thegodet roller, and means mounted on the shaft and connected to both ofthe thread converging guide and the drawing operation aiding unitrespectively for converting rotary motion into reciprocating motion, andthe thread converging guide and the drawing operation aiding unit arerespectively adapted to be slid in the direction of the axis of rotationof the godet roller with these means;

[0034] (l) Means for synchronizing the thread converging guide and thedrawing operation aiding unit comprises at least two driving motor,shafts respectively mounted on the respective driving motors in thedirection of axis of rotation of the godet roller, and means mounted onthe respective shaf ts and connected to the thread converging guide andthe drawing operation aiding unit respectively for converting rotarymotion into reciprocating motion, and the thread converging guide andthe drawing operation aiding unit are respectively adapted to be slid inthe direction of the axis of rotation of the godet roller with thesemeans;

[0035] (m) Means for moving the thread converging guide and the drawingoperation aiding unit simultaneously in (1) comprises at least two phasedetecting means for detecting that the shaft mounted on each drivingmotor rotates to the prescribed position, and adapted to stop therotation of the shaft provided with the one of the phase detecting meanswhen the prescribed position is detected by one of the phase detectingmeans, and to rotate the stopped shaft when the prescribed position isdetected by the other one of the phase detecting means;

[0036] (n) The cycle of the reciprocating motion of the threadconverging guide and the drawing operation aiding unit is not less than5 seconds;

[0037] (o) The thread converging guide and the drawing operation aidingunit are adopted to be used for the tread including at least two linesof thread; and

[0038] (p) The drawing operation aiding unit is a thread entanglingdevice.

BRIEF DESCRIPTION OF THE DRAWINGS

[0039]FIG. 1 is a schematic front elevation of the spinning/drawingdevice provided with a thread traversing device according to theinvention;

[0040]FIG. 2 is a schematic side view of the apparatus shown in FIG. 1;

[0041]FIG. 3 is a schematic perspective view of the thread traversingdevice according to the embodiment of the invention;

[0042]FIG. 4 is a schematic perspective view of the thread traversingdevice according to the embodiment of the invention; and

[0043]FIG. 5 is a block diagram of controlling means for a phasedetecting means.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044] The method of manufacturing synthetic fiber according to theinvention and the details of the thread traversing device will bedescribed below.

[0045] The synthetic fiber provided for the manufacturing methodaccording to the invention includes threads formed of polyamide,polyester, polyolefin, and alamid, but it is not limited thereto as faras it is such material that the formed thread can be drawn/heat treatedby the use of godet rollers.

[0046] The surface roughness Ra of at least two sets of godet rollersout of the godet rollers used in the invention have to be between 0.5and 5 μm, more preferably, between 1 and 3 μm.

[0047] A set of godet rollers here means a set of rollers having thesame speed of revolution for winding the thread by more than one turnfor example as the first godet roller (18 a and 18 b) shown in FIG. 1.

[0048] The surface roughness Ra is calculated, according to JISB0601, byproviding a Surfcorder SE 1700 manufactured by Kosaka Lab. and measuringthe section curve using a sensing pin with radius 2 μm at a feedingspeed of 0.5 mm/s and a cut-off of 0.8 mm or 2.5 mm to obtain the curveof the surface roughness of the godet roller.

[0049] When performing multistage drawing, if the surface of the godetrollers on which drawing is performed has roughness in this range,drawing is performed not only between rollers, but also while the threadis wound on the rollers. When Ra is smaller than 0. 5 μm or larger than5 μm, since the frictional force generated between the thread and theroller increases, drawing of the thread on the roller becomesincreasingly difficult, and thus it becomes difficult to preventgeneration of a single filament breakage to obtain a high-strengthfiber. The surface roughness Ra in the range between 1 and 3 μm is morepreferable since the frictional force further decreases. By setting thesurface temperature of at least one set of godet rollers out of two setsof godet rollers to at least (the melting point of synthetic fiberthread−70° C.), heat treatment can be performed on the surface of theroller effectively.

[0050] The melting point of the thread here is obtained from a trace ofvariations of heat quantity obtained by melting 2 mg of sample by theuse of DSC-7 type manufactured by Perkin Elmer Inc., quenching andsolidifying it by liquid nitrogen, and scanning the sample at the speedof 20° C./min., which is regarded as a temperature at a maximumendothermic peak.

[0051] The temperature below this value (the melting point of syntheticfiber thread−70° C.) is not preferable for the manufacture of industrialfiber, which is the object of the invention, from such reasons thatstable drawing cannot be performed, and heat dimension stability of thedrawn yarn is lowered due to insufficient heat treatment. Whenperforming heat treatment under such a high temperature condition, aheat-transformed matter caused by spinning oil attached on the thread isaccumulated on the surface of the godet roller, which leads to increasein a single filament breakage or thread breakage, but according to theinvention, accumulation of such transformed spinning oil may beprevented by reciprocating the thread in the direction of the axis ofrotation of the godet roller. In other words, according to theinvention, transformation and accumulation of residue of spinning oilmay be prevented by organic unity of the constructions described above,and thus the manufacture of high-strength industrial fiber may beperformed stably. When the surface roughness Ra of the roller forperforming the heat treatment is smaller than 0.5 μm, the contact areabetween the traveling thread and the roller increases. Therefore, evenwhen the thread is moved in the direction of the axis of rotation of thegodet roller, the transformed matter sticks to the surface of theroller, and thus the transformed matter may be accumulated on both endsof the amplitude of the movement, which hinders the effect of theinvention. On the other hands, when the surface roughness Ra of theroller is in the range between 0.5 μm and 0.5 μm, and the thread ismoved in the direction of the axis of rotation of the godet roller,accumulation of transformed spinning oil can be prevented, therebyachieving the object of the invention. In the range between 1 μm and 3μm, the effect of the invention will be more distinctive.

[0052] When the thread is reciprocated by moving the thread convergingguide, occurrence of a single filament breakage due to abrasion as aresult that filaments are separated during movement of the thread guidemay be prevented.

[0053] The thread converging guide here serves to fix up the travelingthread during spinning and drawing of synthetic fiber, and is, morepreferably, a guide for fixing up the spinning thread.

[0054] As the method of reciprocating the thread converging guide, amethod using means f or converting rotary motion into reciprocatingmotion, such as a method of converting rotary motion of the motor toreciprocating motion via a cam, a method of conversing rotary motion ofthe motor to reciprocating motion via a ball screw, a method ofrepeating linear motion of the cylinder to obtain reciprocating motion,and a method of converting to reciprocating motion via a gear providedon the stepping motor may be employed.

[0055] In the case where the total fineness is not less than 200 dtex,the amount of spinning oil attached on the roller increases, and theeffect of the invention will be distinctive.

[0056] According to the invention, by setting the drawing tensile stressduring the last drawing step to at least 1.4 cN/dtex, furtherdistinctive effect may be obtained. In other words, when the drawingtensile strength is not less than this value, high-strength fiber notless than 6.0 cN/dtex can be obtained and thus the effect of thetransformed spinning oil is distinctive.

[0057] The thread used in the invention is preferably multi-threadincluding at least two lines of thread. When it includes at least twolines of thread, a single filament breakage in each line of thread canbe reduced, and thus a large interactive effect can be obtained.

[0058] The width of reciprocating motion Y (mm) of the thread preferablysatisfies the following expression (1).

XF≦Y≦2(XP−XF)  (1)

[0059] where;

[0060] XF is the width of the thread (mm), and XP is the thread pitch(mm) between the adjacent threads.

[0061] This means the distance from the original position of the threadto the position where the thread leaves the original position, that is,the distance of movement of the thread having the width XF until itreaches the position where the adjacent thread was traveling before.Accordingly, not only effective prevention of accumulated deposits iseffected, but also abrasion preventing effect on the surface of thegodet roller is increased.

[0062] Preferably, the cycle of the reciprocating motion of the threadconverging guide is not less than 5 seconds, and more preferably, notless than 30 seconds from the viewpoint of reduction of damage of thetraveling thread on the godet roller and of reduction of failure rate ofthe traversing device.

[0063] In the manufacture of the industrial fiber having the drawingoperation aiding unit, when the thread is reciprocated in the directionof the axis of rotation of the godet roller while synchronizing thethread converging guide for allowing the thread to pass through beforeand/or after the thread is wound around the godet roller locatedimmediately after the spinning duct and one or more drawing operationaiding units disposed between the plurality of godet rollers, a singlefilament breakage caused by abrasion between the thread and the drawingoperation aiding unit may be prevented.

[0064] The drawing operation aiding unit is a generic name of devicesfor aiding to perform drawing operation smoothly, such as a threadentangling device for preventing a single filament breakage on theroller, a heat treatment cylinder for fixation of a drawing point, aheat plate and a heat treatment cylinder for aiding drawing operation.

[0065] The term “synchronization” in the invention means that the threadconverging guide and the drawing operation aiding unit have a constantrelationship during reciprocating motion, and preferably, both of thethread converging guide and the drawing operation aiding unit have aconstant phase difference during reciprocating motion.

[0066] The direction of the axis of rotation of the godet roller in theinvention means that one component of the movement vector is parallelwith the direction of the axis of rotation of the godet roller.

[0067] The method for reciprocating the thread converging guide and thedrawing operation aiding unit includes the aforementioned method ofconverting rotary motion of the motor to reciprocating motion via a cam,a method of converting rotary motion of the motor to reciprocatingmotion via a ball screw, a method of repeating linear motion of thecylinder to obtain reciprocating motion, and a method of converting toreciprocating motion via a gear provided on the stepping motor.

[0068] As the method of synchronizing the thread converging guide andthe drawing operation aiding unit when using at least two motors orcylinders, a method of detecting the position of the revolving shaft ofthe motor or the cylinder and the position of the thread by the use of asensor to synchronize them, and a method of taking outputs of a motorand of the cylinder out through a shaft and transmitting it to thethread converging guide and the drawing operation aiding unit via a camor a gear to synchronize them are preferable.

[0069] The thread used in the invention is preferably multi-threadincluding at least two lines of thread. When the thread includes two ormore lines of thread, a single filament breakage in each line of threadcan be reduced, and thus a large interactive effect can be obtained. Inthe case of multi-thread including at least two lines of thread asdescribed above, it is preferable to design in such a manner that thethread converging guide is mounted on each line of thread, that is, thesame number as the number of the lines of thread of the threadconverging guide is provided, so that all the lines of threadreciprocate simultaneously.

[0070] In the case where the drawing operation aiding unit is a threadentangling device, it is necessary to position the thread at theintersection of air blow, and accordingly, it is sensitive to thedisplacement of the traveling thread. Therefore, by reciprocating thethread converging guide and the thread entangling device synchronously,the effect such as reduction of breakage of filament becomesparticularly distinctive.

[0071] By setting the width of the reciprocating motion Y (mm) of thethread so as to satisfy the expression (1) described above, accumulateddeposits may be effectively prevented, and the effect of preventingabrasion of the surface of the godet roller may be increased.

[0072] Preferably, the cycle of the reciprocating motion of the threadconverging guide is not less than 5 seconds, and more preferably, notless than 30 seconds from the viewpoint of reduction of damage of thetraveling thread on the godet roller and of reduction of failure rate ofthe traversing device.

[0073] The thread traversing device of the invention will be describedreferring to the drawings.

[0074]FIG. 1 is a schematic front elevation of the spinning/drawingdevice provided with the thread traversing device according to theinvention; FIG. 2 is a side view of the same; FIG. 3 is a schematicperspective view of the second embodiment of the thread traversingdevice of the invention; FIG. 4 is a schematic perspective view showingthe third embodiment; and FIG. 5 is a block diagram of controlling meansfor a phase detecting means according to the embodiment shown in FIG. 4.

[0075] The thread traversing device of the invention is to be useddirectly in a method of manufacturing synthetic fiber described abovefor reciprocating (traversing) the converging guide for allowing thethread to pass through before and/or after the thread is wound aroundthe godet roller located immediately after the spinning duct, andtraversing one or plurality of the drawing operation aiding unitsynchronously therewith.

[0076] In other words, the thread traversing device of the invention isa unit for preventing accumulation of extraneous matters on the surfaceof the godet roller during spinning/drawing of the thread of syntheticfiber, comprising means for synchronously reciprocating a threadconverging guide in the direction of the axis of rotation for allowingthe thread to pass through before and/or after the thread is woundaround the godet roller located immediately after the spinning duct, anda drawing operation aiding unit disposed between a plurality of godetrollers.

[0077] As shown in FIG. 1 and FIG. 2, each of a plurality of threads ofsynthetic fiber (23) is spun out from a spinning duct (1), fed withspinning oil by the oiling rollers (2), passed through the convergingguides (6) mounted on the mounting board (3), pre-stretched between thefirst godet roller (18) and the second godet roller (19), drawn betweenthe second godet roller (19) and the third godet roller (20) in thefirst stage, then drawn between the third godet roller (20) and thefourth godet roller (21) in the second stage, relaxed between the fourthgodet roller (21) and the fifth godet roller (22), and wound on thewinder (W/D). Between the second godet roller (19) and the third godetroller (20), there is provided a drawing operation aiding unit (5) suchas a thread confounding device. However, the positions of the convergingguide and the drawing operation aiding unit of the invention are notlimited thereto.

[0078] As shown in FIG. 2, there is provided means for moving theconverging guide (6) and the drawing operation aiding unit (5) inparallel synchronously, that is, means comprising a driving motor (4), ashaft (8) mounted on the driving motor (4) in the direction of the axisof rotation of the godet roller, and two cams (7) mounted on the shaft(8) and connected respectively to the converging. guide (6) and thedrawing operation aiding unit (5), and such means can move theconverging guide (6) and the drawing operation aiding unit (5)accurately synchronously, so that the thread (23) reciprocates in thedirection of the axis of rotation of the godet roller with respect tothe traveling thread.

[0079]FIG. 3 shows the second embodiment of the thread traversing deviceaccording to the invention. In this device, the shaft (8) is mounted onthe driving motor (4). Though the driving motor (4) and the shaft may bein direct contact with each other, it is preferable to provide a speedreducer (9) therebetween as shown in the figure since a desiredrotational speed can be obtained, and in this arrangement, the travelingthread can be moved at sufficiently slow speed so as not to be damaged.

[0080] The shaft (8) mounted in the direction of the axis of rotation ofthe godet roller is provided with two cams (7 a, 7 b), and the drawingoperation aiding unit (5) mounted on the drawing operation aiding unitmounting board (10) and the converging guide (6) mounted on theconverging guide mounting board (3) are in contact with the respectivecams (7 a, 7 b) via the sliding rollers (13 a, 13 b) providedrespectively on the mounting board (10, 3).

[0081] The drawing operation aiding unit mounting board (10) is mountedon the stationary slide rail (11) so as to slide along the length of theshaft (8).

[0082] In addition, the converging guide mounting board (3) is mountedon the slide bearing (12), which is also stationary, by the use of asliding shaft (14), so as to slide along the length of the shaft (8).

[0083] Therefore, with the arrangement described above, the convergingguide mounting board (3) and the drawing operation aiding unit mountingboard (10) are slid along the length of the shaft (8) respectively bythe slide bearing (12) and the sliding shaft (14) and by the slide rail(11) in association with the movement of the sliding rollers (13 a, 13b) provided on the converging guide mounting board (3) and the drawingoperation aiding unit mounting board (10) along the grooves on the twocams (7 a, 7 b) which is rotated by the driving motor (4), and theconverging guide (6) and the drawing operation aiding unit (5) arereciprocated synchronously in the direction of the axis of rotation ofthe godet roller.

[0084]FIG. 4 shows the third embodiment of the thread traversing deviceof the invention. In this device, the converging guide (6) and thedrawing operation aiding unit (5) are provided respectively on theseparate shafts (8 a, 8 b)mounted respectively on the separate motors (4a) and (4 b) via the separate cams (7 a, 7 b) respectively so as to makea reciprocating motion, and phase detecting means for detecting that therespective cams (7 a, 7 b) are rotated to the prescribed positions aremounted respectively, so that the control panel (17) shown in FIG. 5synchronizes the converging guide (6) and the drawing. operation aidingunit (5) by stopping the rotation of the shaft provided with the one ofthe phase detecting means when the prescribed position is detected byone of the phase detecting means, and rotating the stopped shaft whenthe prescribed position is detected by the other one of the phasedetecting means.

[0085] In other words, in the third embodiment, the converging guide (6)and the drawing operation aiding unit (5) are reciprocated in the samemanner as means in the first embodiment other than the point that theyare driven by the separate driving motors (4 a, 4 b).

[0086] The phase detecting means in the third embodiment may beconstructed as follows. The cams (7 a, 7 b) are provided with detectedportions (16 a, 16 b) of the proximity sensors respectively, and theproximity sensors (15 a, 15 b) are mounted respectively on the portionsthat are not rotated by the driving motors (4 a, 4 b) such as speedreducers (9 a, 9 b). The positions to which these proximity sensors (15a, 15 b) are mounted are discretionary as far as they are not rotated bythe driving motors (4 a, 4 b). For example, they may be mounted on thebearing portions as well as the speed reducers (9 a. 9 b), or may bemounted on the body of the drawing machine.

[0087] When the respective cams (7 a, 7 b) are rotated and the detectedportion (16 a) and the proximity sensor (15 a) or the detectedportion(16 b)and the proximity sensor(15 b)face toward each other, asignal supplied from the proximity sensor(15 a,15 b) is reflected on thedetected portion (16 a,16 b) and detected by the proximity sensor (15a,15 b).

[0088] When the proximity sensor detected the opposed detected portion,a detected signal is supplied to the control panel (17). The controlpanel (17) is, as shown in FIG. 5, connected to the proximity sensor (15a) and the proximity sensor (15 b), and to the driving motor (4 a) andthe driving motor (4 b),and constructed in such a manner that when adetected signal is supplied by one of the proximity sensors (15 a) forexample, the rotation of the driving motor (4 a) provided with the oneof the proximity sensors (15 a) is stopped, and when a detected signalis supplied by the other proximity sensor (15 b), the stopped drivingmotor (4 a) is rotated.

[0089] The proximity sensor to be employed in the invention ispreferably a photosensitive proximity sensor. However, as far as itachieves the desired object, it may be of capacitance type or magnetictype.

[0090] According to the third embodiment, the converging guide (6) andthe drawing operation aiding unit (5) reciprocate in accuratelysynchronously. When there are provided a plurality of drawing operationaiding units, the rotation is stopped sequentially from the drivingmotor on which the proximity sensor which supplied a detecting signalfirst is mounted, and when the last detecting signal was supplied withinone to-and-fro motion, all the driving motor which had stopped mustsimply be driven by the control panel.

[0091] The third embodiment is effective when both of the convergingguide and the drawing operation aiding unit cannot be driven easily byone shaft.

[0092] Preferably, the cycle of the reciprocating motion of the threadtraversing device according to the invention is at least 5 seconds, andmore preferably, at least 30 seconds from the viewpoint of reduction ofdamage of the traveling thread and of reduction of failure rate of thetraversing device.

[0093] In addition, in order to convert a rotational motion of the shaft(8) into a reciprocating motion, a ball screw or a gear may be employedinstead of the cam (7), and it is not limited thereto as far as it canachieve the desired object. However, the use of cam is preferable fromthe viewpoints of the cost and ease of access. The traversing width ofthe converging guide and the drawing operation aiding unit may be variedas desired by varying the shape of the cam, and the converging guide andthe drawing operation aiding unit may be synchronously reciprocated witha constant phase difference by mounting the respective cams being incontact with both of them with the grooves thereof shifted with respectto the shaft.

[0094] In addition, determining the shape of the cam such that the widthY (mm) of the reciprocating motion of the thread satisfies theexpression (1) described above may lead not only to effective preventionof the accumulated deposits, but also to increased effect to preventabrasion of the surface of the godet roller.

[0095] In the converging guide and the drawing operation aiding unitaccording to the invention, the number of lines of thread is notlimited, but preferably, the multi-thread is used. When multi-thread isused, stain on the godet rollers appears distinctively, and thus theobjective effect can be realized distinctively.

[0096] The invention will bear more preferably effect when the treadentangling unit is used as a drawing operation aiding unit. The reasonis that the thread entangling unit requires that the thread ispositioned at the intersection of air blow, and thus it is sensitive tothe displacement of the traveling thread.

[0097] As means for reciprocating the converging guide and the drawingoperation aiding unit, a fluid cylinder or the like may be used insteadof means using the driving motor, the shaft and the cam. However, interms of repair of the unit or the cost, the method described above ismore preferable.

[0098] As is described thus far, according to a method of manufacturingsynthetic fiber and the thread traversing unit according to theinvention, the godet roller may be maintained in the initial state for along time by preventing accumulation of extraneous matters on the godetroller, the rate of operation and productive efficiency may be increasedby reducing the number of times the machine has to be stopped forremoving extraneous matters, and problems such as a single filamentbreakage or generation of fuzz may be solved and high-strength syntheticfiber of good quality and appearance may be manufactured.

[0099] Among others, it is more effective when manufacturing industrialhigh-strength fiber by a high-speed direct spinning/drawing method,because accumulation of extraneous matters on the godet roller isprevented.

[0100] [Embodiment]

[0101] The invention will be described in detail referring toembodiments and comparative examples.

[0102] The evaluation of each characteristic in the followingembodiments was made in the following methods.

[0103] [Surface Roughness]The surface roughness of the godet roller wascalculated, in accordance with JISB0601, by obtaining the roughnesscurve on the surface of the godet roller from the section curve measuredby the use of Surfcorder SE1700 manufactured by Kosaka Lab. with asensing pin of 2 μm radius, a feed rate of 0.5 mm, and a cut-off of 0.8mm or 2.5 mm.

[0104] [Melting Point]

[0105] The melting point was obtained from a trace of variations in heatquantity obtained by melting 2 mg of sample by the use of DSC-7 typemanufactured by Perkin Elmer Inc., quenching and solidifying it byliquid nitrogen, and scanning the sample at the speed of 20° C./min.Temperature at the maximum endothermic peak was regarded as the meltingpoint. The melting point of the drawn yarn obtained by the invention was250° C.

[0106] [Temperature of Godet Roller]

[0107] The temperature on the surface of the godet roller was measuredby the use of a contact thermometer.

[0108] [Tensile Stress of Drawing]

[0109] The tensile stress of drawing was obtained by measuring a tensilestress of the traveling thread between the third godet roller and thefourth godet roller by the use of HS-3000, which is a tension metermanufactured by EIKO SOKKI, and then divided by the total olenier of thedrawn thread.

[0110] [A single filament breakage]

[0111] The number of breakage was counted by a single filament breakagedetector, and expressed by the number of breakage per 10,000,000 m.

[0112] [Contamination of the Roller]

[0113] Stain on the roller along the thread passage was visuallyobserved every 24 hours, and classified into “lightly stained” markedwith A, “normally stained” marked with B, “heavily stained and causingsignificant shaking of the tread” marked with C.

[0114] [Breakage of Thread]

[0115] The number of times of breakage of the thread per day wascounted.

[0116] [Strength of yarn]

[0117] The strength of yarn was measured based on JIS L-1017 (1995). TheS-S curve was obtained using Tensilon tensile tester manufactured byOrientec Co., with the sample having the length of 25 cm at the tensilespeed of 30 cm/min., and read the value from the obtained S-S curve.

[0118] [Heat Shrinkage]

[0119] A skein of obtained yarn was provided and was left stand for atleast 24 hours in the temperature regulated room of 20° C., 65% RH, andthen was measured with a load which corresponds to 0.1 g/d of the sampleapplied thereon. After leaving the sample having a length of L0 stand inthe oven at 150° C. for 30 minutes without any tension applied thereon,it was taken out of the oven and left stand for four hours in thetemperature regulated room. Then the same load as described above wasapplied thereon again, and the length L1 was measured. Then, the rate ofshrinkage by dry heat was calculated using the following expression.

Rate of heat shrinkage (%)={(L0-L1)/L0}×100

[0120] [Embodiment 1]

[0121] Polyethylene terephthalate chip having intrinsic viscosity (IV)of 1.19 was fed to a extruder type melt spinning machine for spinningtwo lines of thread simultaneously. It was filtered through a metallicfilter having a pore of 15 μm and spun through a spinneret having 72holes at a spinning temperature of 300° C.

[0122] Then, spun thread was passed under the atmosphere at hightemperature of 300° C. for 350 mm from the surface of the spinneret, andthen quenched and solidified by blowing cold air at about 20° C.thereon. Subsequently, it is applied with spinning oil by an oilingroller, and routed to the first godet roller. The obtained undrawnthread was, without being wound completely, pre-stretched by 1.06 timesin length between the first godet roller and the second godet roller,then drawn by 3.70 times in length between the second godet roller andthe third godet roller, drawn by 1.40 times in length between the thirdgodet roller and the fourth godet roller, relaxed by 1.0% between thefourth godet roller and the fifth godet roller, and finally wound on thewinder two lines of thread simultaneously at the speed of 3300 m/min.,to obtain drawn yarn. The third and fourth godet rollers used here hadCr₂O₃ coated surfaces of Ra=1.0 μm.

[0123] The temperatures of the respective godet rollers were 70° C. forthe first godet roller, 100° C. for the second godet roller, 120° C. forthe third godet roller, 240° C. for the fourth godet roller, no heatingfor the fifth godet roller. The numbers of turns of the thread for therespective godet rollers were, three turns for the first godet roller,three turns for the second godet roller, four turns for the third godetroller, 7 turns for the fourth godet roller, and five turns for thefifth godet roller. A single filament breakage detector is mounted forthe thread being wound on the fifth godet roller to count the number ofbreakage, and the number of breakage of the thread was evaluated aswell.

[0124] In the drawing/heat treatment process described above, theconverging guide (6) provided forwardly of the first godet roller (18)in FIG. 1 was reciprocated, and the thread (23) was traversed on thegodet roller in the direction of the axis of rotation of the godetroller. The converging guide employed was configured as shown in FIG. 3.

[0125] The thread width XF was 5.0 mm, the thread pitch XP with respectto the adjacent thread was 15.0 mm, and the value of 2(XP-XF) was 20 mm.

[0126] As a mechanism for reciprocating the converging guide, the onemounted on the shaft for rotating a cam connected to the convergingguide by the driving motor via the shaft, and reciprocates theconverging guide in the direction of the axis of rotation of the godetroller along the groove on the cam was employed.

[0127] By setting the number of revolution of the shaft to 2 rpm by theuse of the driving motor and the speed reducer, the cycle of areciprocating motion was set to 30 seconds and the traverse width on thewinding roller to 16 mm respectively. These conditions and the resultsof evaluation of stain on the roller, a single filament breakage, threadbreakage, heat shrinkage of the obtained yarn are shown in Table 1.

[0128] In Embodiment 1, as a result of traversing the thread on thegodet roller, the effects such that the condition of the surface of thegodet roller can be maintained in the lightly stained state until thefourth day, and the number of occurrence of a single filament breakageor of thread was distinctively small were discernible.

[0129] [Embodiment 2]

[0130] The thread traversing device used in Embodiment 1 was replacedwith the one having a structure shown in FIG. 3. The position of theconverging guide, the shape of the cam, the number of revolution of theshaft were the same as in Embodiment 1. The drawing operation aidingunit was disposed between the second godet roller and the third godetroller, and reciprocated synchronously with the converging guide. Theseconditions and the results of evaluation of stain on the roller, asingle filament breakage, and thread breakage are shown in Table 1.

[0131] [Embodiment 3]

[0132] The thread traversing unit used in Embodiment 2 was replaced withthe one having a structure shown in FIG. 4. The position of the drawingoperation aiding unit (5) was between the second godet roller and thethird godet roller in FIG. 1. The shape of the cam and the number ofrevolution of the shaft were the same as in Embodiment 1. Theseconditions and the results of evaluation of stain on the roller, asingle filament breakage, and thread breakage are shown in Table 1.

[0133] As a result, the same preferable results as in Embodiment 2 werediscernible as shown in Table 1.

[0134] [Embodiment 4-Embodiment 8]

[0135] The conditions in Embodiment 2 were changed as shown in Table 1.The obtained results are shown in Table 1.

[0136] [Comparative Example 1]

[0137] Melt-spinning process was performed on polyethylene terephthalateunder the same conditions as Embodiment 1 other than those shown inTable 1, and the thread was wound on each godet roller and taken up bythe winder without reciprocating the converging guide. The results ofevaluation of stain on the roller, a single filament breakage, andthread breakage are shown in Table 1. Consequently, in the case wherethe thread was not traversed on the godet roller, the surface of theroller was maintained in lightly stained condition until the second day,but occurrence of a single filament breakage was suddenly increased onthe third day, and thereafter, the thread could not taken up andoccurrence of thread breakage was increased significantly.

[0138] [Comparative Example 2-Comparative Example 6]

[0139] Melt-spinning process was performed on PET under the sameconditions as in Embodiment 2 other than the conditions shown inTable 1. The results are shown in Table 1. TABLE Embodi- Embodi- Embodi-Embodi- Embodi- Embodi- Embodi- ment 1 ment 2 ment 3 ment 4 ment 5 ment6 ment 7 Presence of Air guide N Y Y Y Y Y Y Presence of Traversing UnitY Y Y Y Y Y Y Traversing Width on spinning Roller 16 16 16 8 16 16 8(mm) Reciprocating Cycle (second) 30 30 30 30 30 30 30 Stain on Roller1st day ◯ ◯ ◯ ◯ ◯ ◯ ◯ 2nd day ◯ ◯ ◯ ◯ ◯ ◯ ◯ 3rd day ◯ ◯ ◯ ◯ ◯ ◯ ◯ 4thday ◯ ◯ ◯ ◯ ◯ ◯ ◯ 5th day Δ Δ Δ Δ Δ Δ ◯ A single filament breakage 1stday 5 4 4 4 4 4 5 (points/10000000 m) 2nd day 9 8 9 10 9 10 6 3rd day 1513 13 19 14 18 9 4th day 22 20 21 26 21 26 15 5th day 29 25 25 32 25 3020 Thread Breakage (times/day) 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Third andFourth Godet Roller Ra (μm) 1 1 1 1 0.5 4 1 Temperature of Fourth GodetRoller (° C. 240 240 240 240 240 240 240 Magnification of Drawing(times) 5.2 5.5 5.5 5.5 5.5 5.5 5.2 denier (dtex) 1100 1100 1100 11001100 1100 230 Strength (cN/dtex) 7.0 7.5 7.5 7.5 7.5 7.5 7.0 TensileStress (cN/dtex) 1.6 1.7 1.7 1.7 1.7 1.7 1.6 Heat Shrinkage (%) 6.2 6.76.5 6.5 6.6 6.5 6.2 Embodi- Comp. Comp. Comp. Comp. Comp. Comp. ment 8Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Presence of Air guide Y N Y Y Y Y YPresence of Traversing Unit Y N N Y Y N Y Traversing Width on spinningRoller 8 0 0 16 16 0 8 (mm) Reciprocating Cycle (second) 5 — — 30 30 303 Stain on Roller 1st day ◯ ◯ ◯ ◯ ◯ ◯ Δ 2nd day ◯ ◯ ◯ ◯ ◯ Δ X 3rd day ◯X X ◯ ◯ X — 4th day Δ — — ◯ Δ — — 5th day X — — ◯ X — — A singlefilament breakage 1st day 7 12 5 4 4 5 35 (points/10000000 m) 2nd day 1228 20 7 25 21 60 3rd day 19 60 52 12 32 60 — 4th day 32 — — 28 36 — —5th day 60 — — 30 60 — — Thread Breakage (times/day) 0.3 1.0 1.0 0.2 0.51.4 — Third and Fourth Godet Roller Ra (μm) 1 1 0.3 1 1 6.0 —Temperature of Fourth Godet Roller (° C. 240 240 240 240 240 160 240Magnification of Drawing (times) 5.5 4.9 4.9 4.9 4.7 4.8 4.8 denier(dtex) 1100 1100 1100 1100 1100 1100 1100 Strength (cN/dtex) 7.5 6.0 6.06.0 5.8 5.8 5.8 Tensile Stress (cN/dtex) 1.7 1.4 1.4 1.4 1.3 1.4 1.4Heat Shrinkage (%) 6.5 5.5 5.5 15.5 4.5 5.5 5.5

[0140] [Industrial Applicability]

[0141] As is described thus far, according to a method of manufacturingsynthetic fiber and a thread traversing device of the invention, bypreventing accumulation of extraneous matters on the godet roller, thegodet roller can be maintained in the initial state for a long time andthus the number of times the machine has to be stopped for removingextraneous matter can be reduced to increase the rate of operation andproductive efficiency. In addition, problems such as thread breakage orgeneration of fuzz are solved and thus high-strength synthetic fiber ofexcellent quality and appearance can be manufactured. Especially, whenmanufacturing industrial high-strength fiber by high-speed directspinning/drawing method, accumulation of extraneous matter on the godetroller can be prevented, thereby being preferably applicable to amanufacturing process of industrial high-strength synthetic fiber.

What is claimed is:
 1. A method of manufacturing synthetic fibercomprising the steps of performing multistage drawing/heat treatment onthe thread of synthetic fiber formed by melt spinning using a pluralityof godet rollers, and subsequently winding the obtained thread, whereinat least two sets of godet rollers out of the plurality of godet rollershave surface roughness in the range of 0.5-5 μm, wherein at least oneset of godet rollers out of these godet rollers having surfacetemperatures not less than (the melting point of the synthetic fiber−70°C.) is used, and wherein the thread is reciprocated in the direction ofthe axis of rotation of the godet roller.
 2. A method of manufacturingsynthetic fiber according to claim 1, wherein the tensile stress of thethread is not less than
 1. 4 cN/dtex in the last drawing step of themultistage drawing.
 3. A method of manufacturing synthetic fiberaccording to claim 1 or claim 2, wherein the thread of the syntheticfiber is not less that 200 dtex.
 4. A method of manufacturing syntheticfiber comprising the steps of performing multistage drawing/heattreatment on the thread of synthetic fiber formed by melt spinning usinga plurality of godet rollers, and subsequently winding the obtainedthread, wherein the thread is reciprocated in the direction of the axisor rotation of the godet roller while synchronizing at least one threadconverging guide for allowing the thread to pass through before and/orafter the thread is wound around the godet roller which wind the threadfirst after passing the spinning duct and one or plurality of drawingoperation aiding units disposed between the plurality of godet rollers.5. A method of manufacturing synthetic fiber according to claim 4,wherein the drawing process is a multistage drawing process including atleast two stages.
 6. A method of manufacturing synthetic fiber accordingto any one of claim 1 to Claim5, wherein the thread is multi-threadincluding at least two lines of thread.
 7. A method of manufacturingsynthetic fiber according to any one of claim 4 to claim 6, wherein thedrawing operation aiding unit is a thread entangling device.
 8. A methodof manufacturing synthetic fiber according to any one of claim 1 toclaim 7, wherein the width Y(mm)of reciprocating motion satisfies thefollowing expression (1). XF≦Y≦2(XP−XF)  (1) where; XF is the width ofthe thread (mm), and XP is the thread pitch (mm) between the adjacentthreads.
 9. A method of manufacturing synthetic fiber according to anyone of claim 1 to claim 8, wherein the cycle of the reciprocating motionis at least 5 seconds.
 10. A thread traversing device to be used for amethod of manufacturing synthetic fiber in which the thread of syntheticfiber formed by melt spinning is drawn/heat treated and then wound by aplurality of godet rollers, comprising at least one thread convergingguide for allowing the thread to pass through before and/or after thethread is wound around the godet roller located immediately after thespinning duct, an drawing operation aiding unit disposed between aplurality of godet rollers, and means for synchronizing the threadconverging guide and the drawing operation aiding unit.
 11. A threadtraversing device according to claim 10, wherein the means forsynchronizing the thread converging guide and the drawing operationaiding unit comprises a driving motor, a shaft mounted on the drivingmotor in the direction of the axis of rotation of the godet roller, andmeans mounted on the shaft and connected to both of the threadconverging guide and the drawing operation aiding unit respectively forconverting rotary motion into reciprocating motion, and the threadconverging guide and the drawing operation aiding unit are respectivelyadapted to be reciprocated in the direction of the axis of rotation ofthe godet roller.
 12. A thread traversing device according to claim 10,wherein the means for synchronizing the thread converging guide and thedrawing operation aiding unit comprises at least two driving motors,shaft respectively mounted on the respective driving motors in thedirection of the axis of rotation of the godet roller, and means mountedon the respective shafts and connected to both of the thread convergingguide and the drawing operation aiding unit respectively for convertingrotary motion into reciprocating motion, and the thread converging guideand the drawing operation aiding unit are respectively adapted to beslid in the direction of the axis of rotation of the godet roller.
 13. Athread traversing device according to claim 12, wherein the means forsynchronizing the thread converging guide and the drawing operationaiding unit comprises at least two phase detecting means for detectingthat the shaft mounted on each driving motor rotates to the prescribedposition, and adapted to stop the rotation of the shaft provided withthe one of the phase detecting means when the prescribed position isdetected by one of the phase detecting means, and to rotate the stoppedshaft when the prescribed position is detected by the other one of thephase detecting means.
 14. A thread traversing device according to anyone of claim 10 to claim 13, wherein a speed reducer is provided betweenthe shaft and the driving motor.
 15. A thread traversing deviceaccording to any one of claim 10 to claim 14, wherein the cycle of thereciprocating motion of the thread converging guide and the drawingoperation aiding unit is not less than 5 seconds.
 16. A threadtraversing device according to any one of claim 10 to claim 15, whereinthe thread converging guide and the drawing operation aiding unit areadopted to be used for the tread including a plurality of lines ofthread.
 17. A thread traversing device according to any one of claim 10to claim 16, wherein the drawing operation aiding unit is a threadentangling device.